MySQL：将表的列一对多连接

Question

I have 2 tables ( person + person_products )

where each person has at least 1 product.

Sample person table:

person_id | name
------------------
1         | Alice
2         | Peter
3         | James

Sample person_products table:

id | person_id | description | price
------------------------------------
1  | 1         | iphone 5    | 100
2  | 1         | iphone 6    | 200
3  | 1         | samsung     | 300
4  | 2         | tv          | 110
5  | 3         | oven        | 250
6  | 3         | microwave   | 260

I want to do the following:

SELECT p.person_id, 
some_concat_product_descriptions, 
some_concat_product_prices
FROM person p
LEFT JOIN person_products p on p.person_id = pp.person_id

Expected result:

person_id | concat_product_descriptions | concat_product_prices
---------------------------------------------------------------
1         | iphone 5, iphone 6, samsung | 100, 200, 300
2         | tv                          | 110
3         | oven, microwave             | 250, 260

How can I achieve this?

Answer 1

Use group_concat

SELECT p.person_id, 
       group_concat(pp.description order by pp.description) as concat_product_descriptions,
       group_concat(pp.price order by pp.description) as concat_product_prices
FROM person p
LEFT JOIN person_products pp on p.person_id = pp.person_id
GROUP BY p.person_id

Answer 2

Use group_concat aggregation function . A join is is not needed at all.

select 
  person_id,
  group_concat(description) separator ', ' as concat_product_descriptions,
  group_concat(price) separator ', ' as concat_product_prices
group by 
  person_id